Optogenetic Tool Has Potential for Brain Mapping

An optogenetic tool that can map and track interactions between neurons inside different areas of the brain using low-energy near-infrared (NIR) light could help scientists better understand how different parts of the brain react when a linked area is stimulated.

Previously, methods to deliver optogenetic beams into the brain involved bulky microscopes or complex scanning beams. But the new two-photon, optogenetic stimulator developed by Samarendra Mohanty at the University of Texas at Arlington uses fiber optics to introduce the gene for channelrhodopsin-2 (ChR2), a protein that responds to light, into a sample of excitable cells. Fiber optic infrared light beams can then be used to precisely excite the neurons in a tissue circuit without damaging them.

The tiny tool builds on Mohanty’s previous discovery that NIR light can stimulate light-sensitive proteins introduced into living cells and neurons in the brain.

The new method of using low-energy NIR light enables more precision and a deeper focus than the blue or green light beams often used in optogenetic stimulation, the investigators said. In the brain, researchers could observe responses in the excited area as well as in other parts of the neural circuit; in living subjects, scientists could observe behavioral outcomes, Mohanty said.

His group is collaborating with UT Arlington department of psychology assistant professor Linda Perrotti to apply this technology in living animals.

“Scientists have spent a lot of time looking at the physical connections between different regions of the brain. But that information is not sufficient unless we examine how those connections function,” he said. “That’s where two-photon optogenetics comes into play. This is a tool not only to control the neuronal activity but to understand how the brain works.”

Lab members Kamal Dhakal, Ling Gu and Bryan Black also contributed to the research, which appears as an early posting online in Optics Letters.